Radio station selector



Feb. l0, 1942. E. H. ALLEN 2,272,627

- RADIO STATION SELECTOR Filed March' 24, 1938 3 Sheets-Sheet 2 INVENTQR,5v/PL ,sa Auf/y ATTORNEY Feb. 1o, 1942. y E, H, ALLEN 2,272,627

RADIO STATION SELECTOR ATTO R N EY Patented Feb. 10, 1942 RADIO STATION'SELECTOR Earl H.. Allen, Fanwood, N. J., assis-nor, by mesneassignments, to Condenser Development Corporation, Newark, N. J., a.corporation of New- Jersey Application March 24, 193s, serial No.197,755

(ci. 'i4-1o) .Claims 'Ihis invention relates to a radio station selectorand more particularly to one in which pushbutton manuals, eachrepresenting a given frequency or station, are selectively operable' foractuating the tuning unit of the radio receiver.

The present invention is an improvement on the Radio station selector ofthe copending application of Samuel Cohen and Earl H. Allen, Serial No.193,886, led March 4, 1938.

'Ihe broad object of the invention (as set forth in said copendingapplication) centers about the provision of a push-button type of tuningselector for a radio receiver designedI to operate mechanically in a wayto meet the high accuracy requirements of repeatable tuning selection. Acorrelary broad object of the invention deals with the provision of suchselector which is mechanically simple in construction, capable of beingreliably manufactured by quantity production methods and possessing longusage life under severe operating conditions.

'I'he selector of the present invention is intended for use with avariable tuning unit such as a variable condenser, the rotor of which ismovable over a relatively large arc such as 180 degrees. This rotor isconnected to an operating member which is common to and operable by anyof a plurality of push-button manuals (each representing a givenfrequency or station) translationally movable over relatively shortlinear paths.

One of the main problems in the design of such a push-button selector isthat `of converting and multiplying the relatively short linear ortranslational movement of the push-button manuals or elements into theavailable 180 degree rotation of the rotor of the tuning unit.A Thisentails the provision of suitable mechanism which will readily convertand multiply short linear movements into a 180 degree rotation and onewhich can accomplish this, moreover, with that freedom of play and backlash and with that' minimum of friction loss in the mechanism, whichwill permit the obtaining of high accuracy repeatable operations.

' Two of the ultimate aims of the invention are to meet the needs ofhigh tuning accuracy and repeat accuracy. The mean value of tolerancefor total accuracy (tuning and repeat accuracy) desirable in thepush-button selector (as measured at the condenser rotor) is a tuningvariation of plus or minus 1 kilocycle (a total of 2 kilocycles). With amodern variable condenser employed as the tuning unit of the system,this range, the rotor should be mechanically tunable by the selectorover a 1 degree tolerance. Since the mechanism employed functions notonly to convert motion but to multiply the same, it becomes apparentthat the push-button manuals and the operating member of thel mechanismmust respond to even a higher degree of mechanical operating refinementthan the condenser rotor. By means of the principles underlying thefunctioning of the apparatus of the present invention, these problemsare effectively solved, and in fact it has been ascertained that thetuning accuracy, of the selector mechanism is evenrgreater than thisdescribed desirable tolerance.

'I'he more important phaseof this total accuracy is that of repeataccuracy, which may be defined asv the ability to reproduce apredetermined settlng or tuning over repeated cycles of movement oroperation of the selector mechanism. `To electively accomplish thedesired repeat accuracy, the mechanical linkage between a push-buttonmanual and the condenser rotor must be designed to absolutely eliminateplay and back lash at all points and with a minimum' of friction loss.These requirements are all the more severeidue to the motion convertingand multiplying Vfunctioning of the linkage between any given manual andthe condenser rotor, since any error in the mechanical movement (andreproducibility oi such movement) of the manual is multiplied at thecondenser rotor. By means of the selector structure of the invention,these problems are eiectively solved and a high re'- means that at anaverage point in the tuning peat accuracy is obtained. It has beendetermined that with this selector structure, repeat accuracy of thelcondenser rotor does not exceed a 400 cycle range. Obviously, theequivalent repeat frequency accuracy oi the operating member (and eachpush-buttonmanual) is even higher and comes within a cycle range.

In a radio station selector, provision must be made to enable the userto initially adjust or subsequently readjust the push-button manuals todesired frequencies or stations. It is highly desirable that'suchadjustment be made by the user or operator from the outside of the radiocabinet. Also,vthe adjusting means should desirably be related to thepush-button manuals so that besides b oth being readily accessible tothe user exteriorly of the radio cabinet, they be also mechanicallyassociated in an eiiicient as well as an attractive way, whilepermitting of action or operation kof one independent of the other.Also, since the adjusting means of necessity forms one of the elements(adjustable) in the linkage between the push-button and theultimatelyoperated condenser rotor, it is a further requirement of thestructural combination that each adJusting means be related to itsassociated push-button manual. so that the high tuning and repeataccuracies mentioned may nevertheless be achieved. It is, therefore, afurther object of the invention to provide an improved selectorstructure which solves these additional problems.

A further object of the invention centers about the provision of animproved push-button type of radio tuning selector in which at least oneof the push-button manuals is designed so as to be capable of being usedfor operating the tuning unit over its entire tuning range to enable theset to be tuned to any desired frequency. The provision of an improvedselector structure in which push-button manuals for preselecting astation is appropriately combined with means for tuning a radio set toany desired frequency or station, is desirably accomplished by themechanism ofI the present invention.

In carrying out these objects and principles, the present inventiondeals particularly with improvements comprising, (1) an operating memberwhich is actuatable positively in either direction of its motion by eachof the push-button manuals, (2) an operating member and its linkage tothe tuning unit which form a balanced mechanism capable of stablyretaining any selected position to which it is operated, (3) a selectormechanism embodying latching means for urging the manual into lockingengagement with the operating member and for holding the same in latchedposition, and (4) an improved pushbutton manual and adjusting meanstherefor.

As aforestated, it is desirable that all of these stated problems besolved by means of mechanism simple in construction, capable of beingreliably manufactured in quantity, and possessing long usage life undersevere operating conditions. The selector structure of the presentinvention is designed to meet these additional deslderata.

To the accomplishment of the foregoing and such other objects as mayhereinafter appear, the invention further consists in the structuralcombinations hereinafter sought to be defined in the claims anddescribed more in detail hereinbelow in connection with the appendeddrawings,inwhich:

Fig. 1 is a vertical elevational view of the radio station selector ofthe present invention;

Fig. 2 is a top plan view thereofwith some parts broken away;

Fig. 3 is a right end elevational view thereof taken in cross-section inthe plane of the line 3-3 of Fig. 2 and showing the parts in aninoperative position;

Fig. 4 is a view similar to Fig. 3 in showing the parts in an operativeposition;

Fig. 5 is an enlarged view of a part of the selector mechanism taken incross-section in the plane of the line 5-5 of Fig. 1;

Fig. 6 is a perspective view of one of the pushbutton manuals; and

Figs. 7 to 9, inclusive, are views of details.

Referring now more in detail to the drawings, the radio station selectorof the present invention comprises a unit embodying a supporting frame Fwith which is fixedly associated the tuning unit T such as a variablecondenser, the said frame F supporting all of the elements of theselector system. The essential components of the selector systemcomprise an operating member O connected by means of a linkage mechanismL to the rotor of the tuning unit T, the said operating member O beingcommon to and being actuatable by any of a plurality of push-buttonmanuals, all collectively designated as M. These components of theselector system are designed as aforesaid to readily convert andmultiply short linear movements of the pushbutton elements into a 180degree rotation of the rotor of the tuning unit and to do this with thatfreedom of play and back lash and with that minimum of friction losswhich will permit the obtaining of high accuracy repeat operations,

The frame F is built in simple fashion to provide a firm and rigidsupport. It consists of front and rear walls I2 and I3, an intermediatebrace wall III, all bolted by suitable attaching means such as rivets I5and screws I5', I5 to the side walls I6 and I'I. The rear andintermediate walls I3 and I4 have suitable ledges I3', I4 turned downfrom the top edges thereof to provide a support for the condenser unitT, which latter may be attached thereto in any approved way (see Figs.1, 3 and 4). 'I'he tuning unit T may be of any modern type; and this isillustrated in Figs. 1 and 2 as a condenser of a three-gang type havinga plurality of stator sections s, and a plurality of rotor sections runited to form a single rotor having an operating shaft I9. The

rotor of the condenser is movable over its entire degree tuning range.

One of the important components of the selector mechanism is the meansfor linking the operating member O to the tuning rotor r. The operatingmember O is designed to be movable over an arc of about 45 degrees, and,therefore, the means for linking the operating member to the tuningrotor is made to comprise a mechlinkage mechanism embodying threeelements,

with the relatively movable parts thereof localized to two pivot pointsat which back lash or play is controllably eliminated. This motion multiplying mechanism comprises a long outer element or arm 2l] xedlyjoined at its outer end to the operating member O, a short outer elementor arm 2I fxedly joined at its outer end to the rotor shaft I 9, and alink or intervening element 22 pivotally connected to the outer elementsor arms 20 and 2I. This three-element linkage mechanism is movablebetween the extremes of an open link formation (shown partly open inFig. 4 of the drawings) to a convolute link formation (shown in Fig. 3of the drawings). This linkage mechanism and this described motionthereof enables the desired conversion of a short (45 degrees) arcuatemotion of the operating member, to the full range (180 degrees) arcmotion of the condenser rotor.

In detail, the operating member O consists of a contact plate 23 in theform of a cradle having upper and lower cam or contact faces 24x and242. The cradle 23 is provided at its opposite ends with the supportinghubs 25 and 26 rigidly the condenser stator).

unit T present a balanced coordinated structure which, when moved (bythe push-button manuals) to any selected position in the range, willremain stationary in that position.

The push-button manuals, collectively designated as M, comprise aplurality of push-button elements each representing a given frequency orstation and each linearly or translationally movable to actuate theoperating member O, which set screw 30. rI'he link or intervening member22 is pivotally connected to the arms 20 and 2| by means of the pivotpins 3| and 32. Thus, the operating member O is flxedly united or linkedto the condenser rotor r, except for the two pivot pins 3| and 32, whereall the loose play or back lash may be and is thus localized. The playat these pivot pins 3| and 32 is then eliminated by additionallycoupling the outer elements or arms 20 and 2| by means of the tensioningspring 33 arranged in parallel with the middle link 22, the said springbeing anchored at its opposite ends to extensions of the pivot pins 3|and 32.

Therefore, by this described means all play or back lash in the linkagemechanism L is localized at two controllable points where such play isthen eliminated. This linkage mechanism, eliminating the use of gearsand reducing the 'movable connections to two pivot pins of smalldiameter, also reduces the friction loss between the operating memberand the tunable rotor to a minimum. The desired results are furtherenhanced by providing line contact (squared) bearings in the link 22 forthe pivot pins 3| and l32` (see Figs. 3 and 4). It will be noted thatthe linkage elements are also exceedingly simple in structure and may bereadily assembled for use, thus enabling the manufacture of these partswith uniformity in quantity production.

One of the improvements 1n the selector of the present invention residesin 'the design of the operating member O whereby it may be operatedpositively in either direction of its rotation. It

is to this end thatthe contact plate .23 is made in cradle form,provided with the upper and lower cams or contact faces 241 and 242. Apushing engagement of the upper cam face 241 by a suitable camvorcontact member will cause rotation of the cradle 23 in one direction (tocause the condenser rotor r to mov'e towards interleaving relation withthe condenser stator s), while a pushing engagement of the lower camface 242 by a suitable cam or contact member will cause rotation of thecradle 23 in the opposite or reverse direction (to cause the condenserrotor to move out of interleaving relation with The cam faces 241 and242 are also so related that when either cam face serves as the engagedor actuating face, the other cam face serves or acts (in conjunctionwith its contact member) as a means for stopping the operating member Oin its selected position. Elimination of play and minimizing of frictionloss in the operation of the member O is obtained by the adjustable ballbearings 2li and 29 aforesaid, one of which is shown in detail in Fig. 9of the drawings; ball bearing'28 directly supports the hub plate 25 andball bearing 29 supports the hub plate 26 by way of the lower end of thearm 20 (see Figs. 3 and 4).

This combination of the operating member O (operable positively ineither direction of its rotation), the linkage mechanism L and thetuning ticularly to Figs. 5 and 6 of the drawings, each latter is commonto all of the push-button elements. In the exemplication of theinvention shown in the drawings, seven push-button elements are shown,six of which are employed for preselecting given stations orfrequencies, and the remaining one of which (the right end one of Figs.1 and 2) is employed when it is desired to operate the tuning unit toany point in its tuning range. Since the rst six push-button elementsare identical in structure and operation, only one of these need bedescribed, such a one being shown in enlarged detail in Figs. 5 and 6 ofthe drawings. The seventh manual used to cover the full tuning range ofthe condenser is shown'in detail in Figs. 3 and 4 of the drawings.

Referring generally to Figs. 1 and 2, and parpush-button manual'comprises a key 34 slidable in keyways 35 and 36 cut in the front andbrace walls |2 and I4 respectively of the frame F, the

saidkey 34 being provided at its front end with 'an operating button A31and at its rear end with a camor contact member 38, the said cam orcontact member being intendedfor cooperation with the contactor camfaces 24 and 24'4 of the cradle 23. In the drawings, these keys areshown in their retracted or inoperative position.

The structure and operation of each push-buttonmanual and its relationto the operating member O are so designed that all play is delinitelylocalized and made controllable and then eliminated at the controlpoints. To avoid any perceptible rotational component of play, thepush-button manuals are made responsive only to a translational slidablemovement. This is preferably accomplished by making each key from sheetmaterial (of relatively thick stock, however), the key having asubstantial height o r vertical dimension. With this construction, eventhough there is slight play of the key in the keyways. (enabling theobtaining of a low friction loss) there is substantially no rotationalcomponent of this play. By means of this structure, the effective playmay be localized in the vertical plane of the key; and the relationbetween the manual and the operating-member of the exemplied structureis made such 'that the play may be localized, controlled and eliminatedat the latching member for the manual at the point indicated at :l: inFig. 4. This will be explained further herenbelow in connection with adescription of the operation of the latching member.-

To actuate positively the operating member O in either direction'of itsrotation, the contact ymember 38 is shaped to provide upper and lowercam or contact elements 381 and 382 positioned to cooperate respectivelywith the cam or contact faces 241 and 242 of the cradle 23. When aselected one of the manuals M isactuated (by pushing a push-button 31),and its key is depressed to its operating position, rcontact element 381will engage contact face 241 or contact element 382 will engage contactface 242, depending upon the then or previously assumed position of thecradle 23 and will accordingly cause the rotation of the cradle 23 andoperating member O in either one 4 direction or the other. If theengagement is that of contact parts 381 and 241, cradle 23 will be movedclockwise (as shown in Fig. until contact parts 382 and 242 are causedto meet, at which time the contact element 38 and cradle 23 are lockedone within the other, the contact parts 382 and 242 thereby servingas astop means forI stopping the operating member Q in its selectedposition. Conversely should the engagement be first that of contactparts 382 and 242, cradle 23 will be moved counter-clockwise untilcontact parts 381 and 241 are caused to meet, at which time the contactelement 38 and cradle 23 are locked one within the other. Due to thefact that the operating member 0 will stably remain in any selectedposition to which it is thus operated, the push-button manual could, ifdesired, be released and returned to its retracted or inoperativeposition. It is desired, however, to hold or lock the operating member Oin its thus selected position, and to this end the push-button key islatched or locked in its operative position as will be described furtherhereinafter.

As aforestated, provision is made to enable the user to adjust orreadjust the push-button manuals to desired frequencies or stations, andit is an object of the invention to provide a construction in which theadjustment may be made from the outside of the radio cabinet. Toaccomplish this, each contact member 38 is made adjustable and eachmanual is provided with an adjusting element 39, the inner end of whichcontrols the position of the contact member 38 and the outer end ofwhich projects from the frame F and from the radio cabinet C (see Figs.3 and 4) so as to be accessible to the user when adjustment is desiredto be made.

The contact member 38 is made adjustable by rotatively mounting the sameon the inner end of the key 34, the rivet 40 (see Figs. 2 and 6) forminga pivot shaft and axis for this purpose. The adjusting element 39specifically consists of a rod-like member having a threaded portion 391which directly engages at its inner end the lower leg of the contactmember 38. A strong tension spring 4I anchored at its opposite ends tosuitable parts of the key 34 and contact member 38 exerts a pull onthelatter to hold the same in engagement with the adjusting rod 39. Thisadjusting rod 39 is supported on the key 34 for rotation andlongitudinal movement. As shown, the key 34 is provided with the spacedlugs 42 and 43, both bored and the latter threaded to carry theadjusting element 39 for the desired movement. The operating button 31received by the two tines 341 and 342 of the key 34 is bored at 31',this bore registering with the adjusting element 39. With this describedconstruction, a screw driver may be inserted through the bore 31 of thepush-button 31 to engage the head of the adjusting element 39 to rotatethe latter and effect incremental longitudinal movements thereof. 'Ihiswill correspondingly incrementally rotate (in one direction or theother) the contact member 38about the rivet shaft 40. The axis of therivet shaft 4U is in alignment with the ball bearing axis of the cradle23 when these elements are locked one within the other, and hencerotation adjustment of the contact member 38 predetermines the selectiveposition to which the operating member O is actuated. Preferably, theadjusting elementof each of the manuals is longitudinally movable on themanual over a distance which will cover the full range of adjustment ormovement of the rotor, of the tuning element.

Although the operating member O and its linkage to the tuning unit willstably retain any position to which it is actuated, it is desired tolock the same by suitable latching means in the position to which it isselectively operated. 4Such latching means is required for the operationof the push-button manual as shown in Figs. 3 and 4, and is desired forthe remaining manuals for the purpose of locking the operating member4against vibrating displacement of the kind to which it may be subjectedwhen employed in automobile receivers. In the structure of the presentinvention, this latch means is related to the push-button manuals toaccomplish a number of desired results .among which are the eliminationof .any play in the vertical plane of lthe latch memb'ers and thelocking of the actuating member of the manual into the coacting parts ofthe operating member, the latch member thus serving the function ofholding the tuning rotor in its selected position and causing the sameto take exactly the same position in repeated operations.

This latch means comprises a roller 44 rotatably mounted in a U-shapedbracket 45 which latter is oscillatably mounted on a shaft 46 journaledin plates 41, 41 attached to the walls I6 and I1 of the frame F. Theroller 44 cooperates with a projection or lug 48 formed' integrally witheach of the -slidable keys 34, each lug having an unlatching face 49 anda latching face i0 thereon. The bracket 45 with the latching rollerthereon is constantly urged to the positions particularly shown in Figs.3 to 5 of the drawings by means of a spring 5| which is anchored at itsopposite ends to suitable points of the bracket 45 and the brace wallI4, as most clearly shown in Fig. 5 of the drawings.

With this described construction, an inward` push applied to the button31 of any manual produces, rst, an engagement between the actuatingmember 38 of the manual and the cradle portion 23 of the operatingmember to rotate the latter either in the one direction or the other,depending upon its previously assumed position, the finally assumedposition of these parts being determined by the position to which theactuating member 38 of the manual has been adjusted. The initial inwardmovement of a push-button manual causes the latching roller 44 to rideon the unlatching face 49 of the lug 48 thereby effecting the movementof the latching roller to an elevated position to thereby release anypreviously operated push-button manual. Upon the continued movement ofthe operating manual, the latching roller 44 will engage the latchingface 50 of the manual lug 48; and when the parts have assumed thisposition, the spring 5l urges the latching roller into toggle engagementwith the said latching face 50, the result being that the manual isforced inwardly sufliciently to firmly lock the actuating member 38 ofthe manual into engagement with the cam or contact faces of the cradle23 of the operating member O. This relation of the parts isbestillustrated in Fig. 4 of the drawings.

This latch means is thus active on each of the manuals M for 4urging thesame into and for denitely holding the same in engagement with theoperating member O by a toggle action which is released or broken by theinitial movement of any other manual. The latch means also centers theactuating or contact member 38 o1' the manual with relation to theoperating member and thus controls and eliminates any play in the saiding of the parts, but alsol enables the compensa.`

tion for minor variations in the assembly positions of the differentmanuals. To adapt the latch means to all the manuals, it is desirable tofinally fix the position of the bracket 45 of the latch means after theremaining parts are assembled, and this is accomplished by providing theseparate mounting plates 41, 41 for the shaft 46 of the latching meansand by soldering these plates as indicated at 52 (see Figs. '1 and 8) tothe walls I6 and I1 of the frame F when the position of the shaft 46 isfinally determined.

Each manual M is also provided with a return spring 53 anchored at itsopposite ends to the brace plate I2 of the frame F and to a suitablepart of the key 34 by being received in apertures inv these parts, as ismost clearly shown in Fig. of the drawings. The latch face 50 of eachkey 34 may also serve as a stop coacting with a cushion stop plate 54mounted on the front wall I2 of the frame F (see particularly Fig. 5).

In Figs. 3 and 4 of the drawings, there is depicted the operation ofthat push-button manual which is employed for manually tuning thecondenser to any desired frequency. This pushbutton manual embodies thesame structure as that of the presetting manuals, except that thepush-button element is provided with an operating knob for rotating theadjusting element of the manual. TheV parts of this manual which aresimilar to those of the manuals shown in Figs. 5 and 6 of the drawingsare designated by similar reference characters, and the descriptionthereof givenabove applies equally thereto, except thatA thescrew-threaded portion 39' of the adjusting element 39 is preferablymade with a larger screw pitch to enable coarse adjustments to be made.

This manual is provided with an operating knob 56 having a tubular shank51 rotatably (but not slidably) mounted in the bearing lug 42 and theinner end of this tubular shank 51 receives the contiguous end ofthescrew-threaded rod 39,

ythe two being joined together by the pin and slot connection 58. Withthis construction, rotation of the operating knob 56 will cause therotation and the longitudinal movementv of the adjusting screw element39.

It will be understood that to operate this manual, it rst has to bepushed (in the same way as the other manuals) from a position shown inFig. 3 of the drawings to the position shown in Fig. 4 of the drawings.With this manual thus pushed into its operative position and therelatched by the latch means, as clearly shown in Fig. 4 of the drawings,rotation of the knob 5B will result in 'rotating by incremental changesthe contact member 38 which, being locked in engagement (at its contactpoints 381 and 382) with the operating member O (at its correspondingcontact faces 241 and 242) will correspondingly rotate by incrementalchanges the operating member O, and thereby move the rotor of the tuningunit to any point of its range so that anydesired station may be tunedin by the operator. It will also be apparent that upon operationthereafter ofany of the other presetting manuals, the latch 44 will beautomatically moved to release the push button manualshown in Figs. 3and 4 to the retracted or inoperative position.

'I'he structure and operation of the radio station selector of theinvention and the various advantages thereof will in the main be fullyapparent from the above detailed description. It

will be seen that the movement of any push-button manual over a short(about one-half inch) linear or translational movement operates theselector mechanism to rotate the condenser rotor to any preset positionwithin its 180 degree rotation range. This operation is accomplished bysimple mechanism inter-related so that there is substantial freedom ofplay and back lash and a minimum of friction loss, all-to the endthatthere may be obtained a high degree of total accuracy in the repeatedoperations of the manuals. All but one of the manuals M are operable forpreselecting a frequency o r station, although any one of these may alsobe manipulated by operation of its adjusting means to tune the tuningunit to any desired frequency. One' 0f thesel manuals is set apart fromthe others and is specially designed for tuning the condenser rotortoany desired station. When theuser or operator desires to adjust orreadjust the manuals, he may do so from the outside of the cabinet. Nogears are employed in the mechanism of the selector; and the elements ofthe operating mechanism of the selector are so designed by theiruniformity and simplicity as to be capable of being manufactured inlarge quantities and assembled with facility and rapidity. Moreover, allof the operating elements are rugged in construction and are subject tovery'little wear and tear in the repeated operations to which a seylector of ,this character is normally subjected, thereby affording longusage life. All of the parts are readily'accessible for repair orreplacement.

It will be understood that one of the preferred forms of the inventionhas been shown and described to exemplify the principles of theinvention and that numerous-changes may be made thereto withoutdeparting from the spirit of the invention defined by theappendedclaims.

I claim: i

1. In a radio station selector, a rotatable operating member and atranslationaliy movable push-'button manual for actuating the same, theoperating member comprising a cradle shaped member having two cam orcontact faces spaced thereon on opposite sides of the rotational axisthereof, and an actuating member at the operating endof said manual,said actuating member coaction with the cam or contact faces on theoperating member.

2. In a radio station selector, a rotatable operating member having twocontact parts spaced on opposite sides of the rotational axis thereof,and a translationaliy movable push-button manual for actuating the same,a push-button at the outer end of said manual, the said manual having anactuating member at the inner end thereon, the said actuating memberbeing rotatably mounted on said manual for adjustment about an axiswhich is coincident with the rotational axis of the operating memberwhen the said manual is moved to its operative position, the saidactuating member having two 'contactparts spaced on opposite sides ofthe said axis thereof and adapted for coaction with the contact parts ofsaid operating member, and means carried by said manual for adjustingthe said actuating member about its said axis, the said means having apart projecting into said push-button and accessible therethrough.

3. In a radio station selector, in combination with a tuning device, aframe, a manual for'moving the tuning device toa predetermined position,said manual being slidably mounted in said frame, an actuating member atthe inner end of said manual, a push-button on the outer end of saidmanual, the said actuating member being rotatably mounted on said manualfor adjustment, the said member having two actuating parts spaced onopposite sides of the rotational axis thereof, and an adjusting screwcarried by said manual for adjusting the said actuating member about itssaid axis, the head of said adjusting screw projecting into saidpush-button and accessible therethrough.

4. In a radio station selector, in combination with a tuning device, aframe, a manual for moving the tuning device to a predeterminedposition, said manual being slidably mounted in said frame, an actuatingmember at the inner end of said manual, the said actuating member beingrotatably mounted on said manual for adjustment, the said member havingtwo actuating parts spaced on opposite sides of the rotational axisthereof, a rotatable element carried by said manual vengaging thesaidactuating member for adjusting the same about its said axis, and atensioning means on said manual for holding the said member inengagement with the adjusting element.

5. In a radio station selector, in combination with a tuning device, aframe, a manual for moving the tuning device to a predeterminedposition, said manual being slidably mounted in said frame, an actuatingmember at the inner end of said manual, a push-button on the outer endof said manual, the said actuating member being rotatably mounted onsaid manual for adjustment, the said member having two actuating partsspaced on opposite sides of the rotational axis thereof, an adjustingscrew carried by said manual having a part engaging the said actuatingmember for adjusting the same about its said axis, and a spring on saidmanual for tensioning said member int-o engagement with the adjustingscrew, the head o! the adjusting screw projecting into said push-buttonand accessible therethrough.

